This invention relates to material handling devices. More specifically, this invention is a lift assist device that, among other components, includes a sensory glove and a controller. The sensory glove is worn by an operator and measures the vertical force that the wearer is imposing on an object that is being maneuvered by the lift assist device or on the lift assist device itself. The measured force is then transmitted in terms of radio frequency (RF) signals to the controller of the lift assist device. The lift assist device lowers and lifts the load so always the human operator exerts a pre-programmed small portion of the force, and the actuator of the material handling device provides the remaining force. Therefore, the actuator of the lift assist device adds effort to the lifting task only in response to the operator""s hand force either on the object that is being maneuvered by the lift assist device or on the lift assist device itself.
A new class of material handling devices is described in U.S. Pat. Nos. 5,915,673 and 5,865,426 (Kazerooni), where the human operator force on the material handling device is amplified electronically by use of a computer to drive the material handing device. FIG. 1 shows a lift assist device 17 according to specifications of U.S. Pat. Nos. 5,915,673 and 5,865,426. At the top of the device, a take-up pulley 18, driven by an actuator 28, is directly attached to a ceiling, wall, or overhead crane. Encircling pulley 18 is a line 26. Attached to line 26 is a sensory end-effector 46, that includes a human interface subsystem (including a handle 23) and a load interface subsystem, which in this embodiment includes a pair of suction cups 60. Human interface subsystem is designed to be gripped by a human hand and measures the human force, i.e., the force applied by an operator 24 against handle 23. Load interface subsystem is designed to interface with a load and contains various holding devices. In addition to suction cups 60 shown in FIG. 1, hooks and grippers are examples of other means that connect to load interface subsystems. Human interface subsystem contains a sensor (described in U.S. Pat. Nos. 5,915,673 and 5,865,426) that measures the magnitude of the vertical force exerted by human operator 24. A signal representing the human force imposed on sensory end-effector 46 by operator 24, as measured by the force sensor in handle 23, is transmitted to controller 20, via signal cable 48, which controls actuator 28 of lift assist device 17. A cable 21 is used for communication between actuator 28 and controller 20. Controller 20 causes lift assist device 17 to move sensory end-effector 46 and load (box 45) appropriately so always only a pre-programmed small proportion of the load force is supported by human operator 24, and the remaining force is provided by actuator 28 of the material handling system. If the operator""s hand pushes upwardly on handle 23, take-up pulley 18 moves sensory end-effector 46 and box 45 upwardly. If the operator""s hand pushes downwardly on handle 23, take-up pulley 18 moves sensory end-effector 46 and box 45 downwardly.
FIG. 2 shows an embodiment of the lift assist device 25 of the invention described here which is different from the devices described in U.S. Pat. Nos. 5,915,673 and 5,865,426. At the top of the device, a take-up pulley 18, driven by an actuator 28, is directly attached to a ceiling. Encircling pulley 18 is a line 26. Attached to line 26 is an end-effector 22. End-effector 22 of the invention here, as shown in FIG. 2, consists of only load interface components that attach to the load; end-effector 22 of this invention does not have any human interface subsystem to measure the human operator force. Instead lift assist device, 25, of this invention has an instrumented glove 10 that is not connected to line 26 or any part of the lift assist device, but is worn by operator 24 and therefore remains with operator 24. Instrumented glove 10 consists of a leather (or cloth) glove 29 with an embedded sensory system 11 (described in detail in later paragraphs). Embedded sensory system 11 in instrumented glove 10 measures the force exerted by human operator 24 on the object being lifted (container 47 in FIG. 2) or on the lift assist device itself. The signal representing operator vertical contact force is then sent to a transmitter circuitry 13 via a signal cable 19. Transmitter circuitry 13 transmits a set of control signals in terms of radio frequency (RF) signals or infrared (IR) signals 15 to a receiver circuitry 16 installed in controller 27 of the lift assist device. Once the transmitted control signals are received, they will then be used for processing and control of actuator 28 as a function of the measured operator vertical contact force. Using the data created by receiver circuitry 16, controller 27 calculates the necessary actuator speed to either raise or lower line 26 to create enough mechanical strength to assist the operator in the lifting task as required.
The important advantage of the lift assist device described here over the devices of U.S. Pat. Nos. 5,915,673 and 5,865,426 is that operator 24 is able to lift and lower a load by contacting any point either on the load (container 47 in the example of FIG. 2), or on the lift assist device itself. FIG. 27 shows an example of the material device where operator 24 is holding onto a handle 187 (connected to line 26) for lifting and lowering loads. In operating the devices described in U.S. Pat. Nos. 5,915,673 and 5,865,426, operator 24 needs to grab a handle which is a part of sensory end-effector 46 and includes a sensor to measure the operator force. End-effector 22 of the invention described here which interfaces line 26 and loads (container 47 in FIG. 2) does not have a sensor to measure operator force; it simply includes tools and equipments to grab loads. The human interaction force with the device is measured in a glove, which is always with the operator. The measured signal, representing the operator force, is then sent to a receiver wirelessly (e.g. via a RF signals) for control of the actuator of the lift assist device.
Since the instrumented glove is an important component of the invention described here, we will describe below the prior arts that relate to the instrumented glove of our invention. Currently, instrumented gloves are used in various applications. For instance, gloves with actuators that create forces on the fingers according to a set of computer instructions are designed to emulate forces on the wearer""s fingers and thumbs in telerobotics and virtual reality applications. U.S. Pat. No. 5,184,319 (Kramer) and U.S. Pat. No. 5,143,505 (Burdea et al.) are patents teaching examples of this application of instrumented gloves.
Another type of instrumented glove device includes sensors that measure kinematics type data (i.e., position, orientation, and posture) of the fingers, thumbs and wrists for various applications. Applications for gloves with embedded sensors measuring kinematics type data include for example: transforming human hand movements into electronic letters and characters, controlling the movement and actions of video characters, providing biofeedback for sports training such as tennis and golf, and assessing the mobility of human and/or animal joints. Examples of transforming human hand movements into electronic letters and characters are taught by, for example, U.S. Pat. No. 4,414,537 (Grimes) and U.S. Pat. Nos. 5,047,952 and 6,035,274 (Kramer et al.). Examples of controlling the movement and actions of video characters are found in the inventions taught by U.S. Pat. No. 5,796,354 (Cartabiano et al.) and U.S. Pat. No. 4,613,139 (Robinson II). U.S. Pat. No. 6,032,530 (Hock) teaches a method and an apparatus with sensors to measure body movement and flexure during kinetic activities. U.S. Pat. No. 4,542,291 (Zimmerman), teaches an optical flex sensor that can be used to detect bending of human movements. U.S. Pat. No. 4,715,235 (Fukui) teaches an electro conductive woven or knitted fabric, which changes its electrical characteristics when stretched and can be used as a switch. And finally, examples of assessing the mobility of human and/or animal joints are taught by, for example, U.S. Pat. No. 4,444,205 (Jackson) and U.S. Pat. No. 4,986,280 (Marcus et al.).
A third type of instrumented glove in the prior art includes glove devices with some sort of sensors to measure the interaction with other objects. Examples include the inventions taught by U.S. Pat. No. 5,581,484 (Prince) describing an apparatus for manually entering information into a computer by generating a virtual keyboard, mouse, graphics tablet or other forms of input data, and U.S. Pat. No. 4,055,905 (Budrose) describing a system that facilitates learning to type. Gloves with sensors to measure the interaction with other objects also include safety and sports training applications, such as taught by, for example, U.S. Pat. No. 6,016,103 (Leavitt) describing a glove to detect whether or not a motor vehicle driver is sleeping, and U.S. Pat. No. 5,669,809 (Townsend) describing a safety glove to be used in conjunction with a cutting machine, U.S. Pat. No. 5,681,993 (Heitman) and U.S. Pat. No. 4,488,726 (Murray) describing gloves for monitoring human gripping force on a golf club or on an aircraft control stick. Similarly, U.S. Pat. No. 6,126,572 (Smith) describes an apparatus for monitoring and displaying information related to pressure exerted at a point of interest during an isometric exercise, and U.S. Pat. No. 5,723,786 (Klapman) describes a boxing glove capable of measuring impact forces. And finally, U.S. Pat. Nos. 5,662,123, 5,449,002, 5,775,332 (Goldman et al.) and U.S. Pat. No. 6,033,370, (Reinbold et al.) describe capacitive sensor which has a plurality of layers forming a force detector which can be embedded in various patients"" shoe, boot, ankle, brace, crutch and handgrip to provide biofeedback to help patients relearn function or prevent atrophy.
Thus, prior to the present invention a need remained in the art for a more versatile device for maneuvering a manual material handling system that requires very little force from the operator and, wherein the operator directs the maneuvering of the material handling device to move an object, by pushing on any point on the material handling device or pushing on the object being maneuvered. Moreover, a system is also further needed to provide assistance for lifting the material handling device proportionally based on the force imposed by the operator, so that the operator provides only a small portion of the total force needed to lift the material handling device. Nevertheless, no prior art instrumented glove type device is designed for assisting manual material handling systems.
The present invention describes a lift assist device for lifting and lowering at least one object, among other components, comprising: an actuator arranged to turn a pulley; a line wound on said pulley and connectable to said object; an instrumented glove wearable by a human hand, wherein said instrumented glove detects a contact force imposed by said human hand on object or a part of said lift assist device, and generates a set of contact signals representing said contact force; at least one transmitter circuitry capable of transmitting a set of control signals representing said contact signals to other locations; and a controller to receive and process said control signals and to generate command signals to control said actuator to cause said device to lower or lift said object. Additional objects, advantages and novel features of the invention will be set forth in part in the description and figures which follow, and in part will become apparent to those skilled in the art on examination of the following, or may be learned by practice of the invention.